This invention relates to an apparatus for at least partial freezing of a food product, more specifically by contacting a surface area of a chilled tray.
For the freezing of food products, use is often made of various types of belt, which support the products during freezing. When the freezing operation is completed, the products are to be removed from the belt, which in many cases involves considerable difficulties owing to the products freezing onto the belt.
A known technique of avoiding the problem with freezing and getting stuck is to use between the belt and the food product a plastic sheet, which can easily be removed both from the belt and from the food product after freezing thereof. This plastic sheet, however, cannot be reused and, besides, can in practice be used only together with a flat belt and therefore does not allow freezing of semiliquid or liquid food products, which require some sort of cavity.
One more technique of obviating the problem with the food products freezing and getting stuck is to utilise a base, which is chilled to such a low temperature that no freezing and getting stuck can take place at all. This technique, however, is relatively energy-intensive since lower temperatures then xe2x88x9290xc2x0 C. are usually required, which makes it necessary to use liquid nitrogen or the like.
The object of the present invention therefore is to provide an apparatus, which allows freezing of both solid and liquid as well as semiliquid food products and besides obviates the problem with freezing and getting stuck without necessitating the use of very low temperatures.
According to the invention, this object is achieved by the apparatus of the type described below.
By dividing, according to the invention, the tray into a plurality of elements, which are juxtaposed and besides are movable relative to each other, it will be possible to remove a frozen food product from the tray, even if the product during freezing has frozen onto the tray. A condition for this is that each of the elements occupies such a small surface in the surface area that a change of the position of at least one element at a time relative to the adjoining element/elements is possible even after the food product part contacting the tray has been frozen.
By arranging the surface area of the tray essentially horizontally during freezing of the food product, the inventive apparatus can be used for both solid and semiliquid or liquid food products. In the case of solid or semiliquid, food products, the elements suitably can form a flat surface area, whereas in the case of liquid, but also semiliquid, food products the elements form a surface area, which comprises a plurality of open cavities for receiving the products. In both cases, the surface area is continuous and unbroken during freezing.
It should be noted that the surface area of the tray when freezing solid food products does not necessarily have to be horizontal, if suitable means are available for holding the product or products in contact with the surface area of the tray during freezing.
In a preferred embodiment, the elements are elongate and, besides, the tray can advantageously be part of a conveyor belt, the longitudinal direction of the elements preferably extending transversely of the longitudinal direction of the conveyor belt. The conveyor belt thus comprises a row of successively arranged trays, which can be connected to each other by means of their neighbouring elements in the same manner as the elements in each pair of adjoining elements in a tray are connected to each other.
The relative movability between the elements can be relatively restricted since the purpose thereof is that each element merely needs to be released from the food product part that has possibly frozen onto the element, which requires a very small relative movement. For instance, the elements can be turnable relative to each other, but alternatively they can be translatable relative to each other, either in a plane extending essentially in parallel with the surface area of the elements or perpendicularly thereto.
In consequence of the present invention, freezing of the tray onto a food product frozen in contact with the tray can be obviated, element by element, or in groups of elements simultaneously, in which case the elements in each group are preferably spaced apart by elements that are not included in the group. By each element occupying a sufficiently small surface, the freezing and getting stuck can easily be obviated with a minimum amount of force and without an essential part of the good product remaining on an individual element.
For reasons of hygiene, the elements may suitably consist of stainless steel, but also other materials with good thermal conductivity can be used. For chilling of the elements, use is preferably made of intensified blowing of cold air towards that side of the tray which is opposed to the side of the tray contacting the food product. Especially, jets of cold air can be employed, which can ensure a sufficiently quick removal of heat from the surface area of the tray.
Typically, the inventive apparatus is used for freezing of merely one layer of the food product where this contacts the tray, in which case final freezing can take place in a conventional freezer. It goes without saying, however, that for certain food products the apparatus may be well suited also for the final freezing.